1. Field
The present invention relates generally to telecommunications, and, more specifically, to multi-carrier communications in wireless systems.
2. Background
A modern communication system is expected to provide reliable data transmission for a variety of applications, such as voice and data applications. In a point-to-multipoint communications context, known communication systems are based on frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and perhaps other multiple access communication schemes.
A CDMA system may be designed to support one or more CDMA standards, such as (1) the TIA/EIA-95 Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System (this standard with its enhanced revisions A and B may be referred to as the “IS-95 standard”), (2) the TIA/EIA-98-C Recommended Minimum Standard for Dual-Mode Wideband Spread Spectrum Cellular Mobile Station (the “IS-98 standard”), (3) the standard sponsored by a consortium named 3rd Generation Partnership Project (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the “W-CDMA standard”), (4) the standard sponsored by a consortium named 3rd Generation Partnership Project 2 (3GPP2) and embodied in a set of documents including TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems, the C.S0005-A Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems, and the TIA/EIA/IS-856 cdma2000 High Rate Packet Data Air Interface Specification (the “cdma2000 standard” collectively), (5) the 1xEV-DO standard, and (6) certain other standards.
Multi-carrier communication systems are being developed and deployed to satisfy the constantly increasing demand for wireless services, including both data services and voice services. A multi-carrier communication system is a system with the capability to transmit information on two or more carrier frequencies. It should be noted that multi-carrier system capability may exist in both downlink and uplink connections; alternatively, a multi-carrier system may have multi-carrier capability only on uplink or only on downlink. “Downlink” signifies forward direction of information transmission, i.e., transmission from the radio network to an access terminal, such as a cellular telephone, PDA, or computer. “Uplink” signifies transmission of information in the reverse direction, i.e., from an access terminal to the radio network.
In some multi-carrier cellular communication systems, an access terminal performing a cold acquisition, (1) attempts to acquire a channel on a system acquisition frequency, (2) receives a listing of available frequency channels on the acquired channel (i.e., via overhead message(s) of the system acquisition channel), (3) uses the AT's internal hashing function to determine which frequency channel from among the available frequency channels to use for communicating with the radio network, (4) acquires the channel on the frequency channel indicated by the hashing function, and then (5) tries to establish a session with the radio network on that latter “hashed to” frequency channel. (Cold acquisition may be performed upon power up, exit from a reset state, or entry into a new cell, for example.) If the AT fails to establish the session, it may again attempt to acquire the system, hash to a channel, and establish a session again, using either the same system acquisition frequency channel as it used initially or another frequency channel from the same “GEO” list of frequency channels as the initial system acquisition frequency channel. Each such attempt uses valuable time, power, and spectrum.
There is a need in the art to reduce the time for establishing a session between access terminals and radio networks. There is also a need to reduce power consumption in access terminals, without unnecessarily impairing communication and other functionality of the access terminals or the radio networks. There is a further need to decrease spectrum use by access terminals and radio networks, also without unnecessarily impairing communication and other functionality of the access terminals or the radio networks.